| ObjectiveThrough special staining,establish a color separation model of lung segments,accurately distinguish and collect lymph nodes in each group,and explore the ways and rules of lymph node metastasis in peripheral lung adenocarcinoma with a diameter of ≤2 cm,to provide references for clinical operation selectio.MethodsWe selected 349 patients with lung adenocarcinoma of peripheral type with tumor diameter≤2cm who underwent lobectomy and systemic lymph node dissection in the Second Hospital of Dalian Medical University from September 2017 to September 2022,and intraoperative isolated specimens were stained with indocyanine green by target segment bronchial injection to establish a lung segment color separation model.All lymph node specimens in each lung segment and lymph node specimens in the mediastinum were extracted for pathological examination to precisely distinguish the lymph nodes in the target segment and to clarify the lymph node metastasis.The histological subtypes of all patients were classified according to the IASLC classification,and the lymph nodes of N1 and N2 groups were accurately classified.Finally,all collected data were analyzed and compared by SPSS software,and multifactorial data such as pathological histological subtype,n-stage,location,percentage of nodal solid components,and degree of differentiation were collected for all patients to assess the relationship between lymph node metastasis and multiple clinical factors.ResultsA total of 349 patients met the inclusion criteria,including 23 patients(6.6%)with lymph node metastasis and 326 patients(93.4%)without lymph node metastasis.Statistical clinical risk factors,gender(P=0.825),age(P=0.367),smoking history(P=0.616),family history(P=0.382),pathological histological subtype(P<0.01),pleural invasion(P<0.01),tumor diameter(P<0.05),degree of differentiation(P<0.01),tumor primary location(P= 0.142)and the solid component of their imaging findings(P< 0.01).Further univariate analysis of which was statistically significant yielded results in which 326 cases(93.4%)were p N0,7(2.1%)were p N1,and 16(4.6%)were p N2.There was significant statistical difference in the relationship between N stage and histopathological subtype(P<0.001),and no lymph node metastasis was observed in microinvasive and mural adenocarcinomas.Invasion of visceral pleura was a risk factor for lymph node metastasis(P < 0.001).In tumor diameter,T1b(1cm < tumor diameter≤2cm)was more likely to have N1(85.7%)and N2(81.3%)lymph node metastasis than T1a(tumor diameter ≤1cm)(P < 0.05).In the relationship between tumor differentiation and lymph node metastasis,highly differentiated tumors did not have lymph node metastasis.With the decrease of differentiation,the proportion of lymph node metastasis increased.There were 14 cases(45.1%)of lymph node metastasis in the poorly differentiated group(P<0.001).In the analysis of the proportion of solid components of tumor(CTR),there was no lymph node metastasis in pure ground-class node(pGGN),and only 1 case(4.3%)of patients with mixed ground-glass node(mGGN)with CTR<50% had lymph node metastasis.With the increase of solid components of tumor,the proportion of people with metastasis gradually increased,There were 25 cases(25.4%)of lymph node metastasis in solid node group(P<0.001).It is further subdivided into N1a(single station metastasis)and N1b(multi station metastasis).N2 is divided into N2a1(without N1 lymph node metastasis,directly jumping to N2 lymph node),N2a2(with N1 lymph node metastasis,and with single station N2 lymph node metastasis)and N2b(multi station N2 lymph node metastasis).The results of the influence on N staging include histopathological subtypes,differentiation degree,and solid components(P<0.05).With the N new stage as the dependent variable and CHAID algorithm,it is concluded that the pathological tissue subtypes are mainly micro-invasive type,wall-attached type,acinar type and papillary type.When pGGN and mGGN with CTR<50% are at the same time,the proportion of lymph node metastasis is very low.However,when the pathological tissue subtypes are solid type,microemulsion type,or mGGN with CTR ≥ 50% and solid nodules,the proportion of lymph node metastasis is high.N1 was further divided into target segment 13-14 lymph nodes,non-target segment 13-14 lymph nodes and 10-12 lymph nodes.There was no case of non-target segment 13-14 lymph nodes metastasis,while target segment 13-14 lymph nodes metastasis was only related to tumor diameter after univariate analysis of multiple clinical factors(P < 0.05).However,there was no significant difference with pathological subtype,differentiation degree,solid component and pleural metastasis(P > 0.05).Conclusion1.For pGGN and mGGN with 10≤ solid component <50%,and whose pathological subtypes are micro-invasive,lepidic,acinar and papillary,segmentectomy can be given priority because lymph node metastasis is rare,and systematic lymph node dissection is not necessary.2.Lobectomy plus systematic lymph node dissection is still the first choice for mGGN with solid component ≥50% and solid nodules,or for solid or micropapillary MGGN.3.Although the positive rate of group 13-14 lymph nodes in the target segment is high,it can not be used as an independent predictor of lymph node staging of lung cancer. |
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